As far as Mahabharata is concerned. After the war ended and Shri Krishan ji was about to return to Dwarika,  Arjun asked Shri Krishan ji to repeat all the knowledge of Gita ji as Arjun expressed his desire to listen to that knowledge again. Arjun further said that he has forgotten the knowledge you gave in the battlefield at the time of war. On this Krishan ji replied that he too doesn't remember what he said in Bhagavad Gita at that time of war and it is not possible for him to say the same knowledge again. Moreover Krishan ji snubs Arjun for not remembering such an important knowledge.
 
Reference: प्रमाण के लिए संक्षिप्त महाभारत (new book) पृष्ठ नं. 667 तथा पुराने के पृष्ठ नं. 1531 पर:-
न शक्यं तन्मया भूयस्तथा वक्तुमशेषतः।।
परं हि ब्रह्म कथितं योगयुक्तेन तन्मया।
(महाभारत, आश्रवः 1612.13)
भगवान बोले - ‘वह सब-का-सब उसी रूपमें फिर दुहरा देना अब मेरे वशकी बात नहीं है। उस समय मैंने
योगयुक्त होकर परमात्मतत्वका वर्णन किया था।‘
संक्षिप्त महाभारत द्वितीय भाग के
पृष्ठ नं. 1531 से सहाभार:
(‘श्रीकृष्णका अर्जुनसे गीता का विषय पूछना सिद्ध महर्षि वैशम्पायन और काश्यपका संवाद‘) -
पाण्डुनन्दन अर्जुन श्रीकृष्णके साथ रहकर बहुत प्रसन्न थे। उन्होंने एक बार उस रमणीय सभाकी ओर दृष्टि
डालकर भगवान्से यह वचन कहा --‘देवकीनन्दन ! जब युद्धका अवसर उपस्थित था, उस समय मुझे आपके
माहात्म्यका ज्ञान और ईश्वरीय स्वरूपका दर्शन हुआ था, किंतु केशव ! आपने स्नेहवश पहले मुझे जो ज्ञानका
उपदेश किया था, वह सब इस समय बुद्धिके दोषसे भूल गया है। उन विषयोंको सुननेके लिये बारंबार मेरे
मनमें उत्कण्ठा होती है, इधर, आप जल्दी ही द्वारका जानेवाले हैं। अतः पुनः वह सब विषय मुझे सुना
दीजिये।
वैशम्पायनजी कहते हैं --अर्जुनके ऐसा कहनेपर वक्ताओं में श्रेष्ठ महातेजस्वी भगवान् श्रीकृष्णने उन्हें
गलेसे लगाकर इस प्रकार उत्तर दिया।
श्रीकृष्ण बोले --अर्जुन ! उस समय मैंने तुम्हें अत्यन्त गोपनीय विषयका श्रवण कराया था, अपने स्वरूपभूत
धर्म सनातन पुरुषोत्तमतत्त्वका परिचय दिया था और (शुक्ल-कृष्ण गतिका निरूपण करते हुए) नित्य
लोकोंका भी वर्णन किया था। किंतु तुमने जो अपनी नासमझीके कारण उस उपदेशको याद नहीं रक्खा यह
जानकर मुझे बड़ा खेद हुआ है। उन बातोंका अब पूरा-पूरा स्मरण होना सम्भव नहीं जान पड़ता। पाण्डुनन्दन
! निश्चय ही तुम बड़े श्रद्धाहीन हो, तुम्हारी बुद्धि अच्छी नहीं जान पड़ती। अब मेरे लिये उस उपदेशको
ज्यों-का-त्यों दुहरा देना कठिन है, क्योंकि उस समय योगयुक्त होकर मैंने परमात्मतत्त्वका वर्णन किया था।
(अधिक जानकारी के लिए पढ़ें - ‘संक्षिप्त महाभारत द्वितीय भाग‘)
 
विचार करें:- उपरोक्त विवरण से सिद्ध हुआ कि श्री कृष्ण जी ने श्रीमद्भगवत गीता का ज्ञान नहीं बोला,
यह तो काल (ज्योति निरंजन अर्थात् ब्रह्म) ने बोला था।
 
Point to note is that the speaker himself doesn't remember what he said at the time but is snubbing Arjun for not remembering it. Had Krishan ji said it himself, he would have remembered it. And then thousands of years later Ved Vyas ji wrote the same knowledge again as Bhagavad Gita. Strange isn't it?
 
Or if Shri Krishan ji is the Supreme God, then how can someone enter his body, whether it be Kaal or anyone else and if you believe Shri Krishan ji gave the knowledge of Gita ji then this crucial point must be considered that why the speaker of Gita ji is asking Arjun to go in to the refuge of some other God whom the speaker of Gita ji himself is considering as the Supreme God.
 
Even after this much discussion if it is not sinking in then probably it won't and I think we will be wasting each others time. If you are happy with what you believe in then let it be.  If you think your path is correct then you shouldn't be concerned at all. There is no force on anyone. For any further information please watch Satsang of Gurudev ji or contact Barwala Ashram, Hisar.
 
Thanks for your time.

@Expose
The philosophy has not been contradicted. Guru Ji has done a translation of that shlok. There are many shloks where Kaal has given misleading information in an effort to convince Arjun to fight. Kaal is answering Arjun's questions and at the same time singing his own glory. During that dialogue he talks about the Supreme God too.
 
Guruji has revealed those shloks where Kaal is talking about the Supreme God and thus contradicting his own theory. Kaal himself claims that he is Kaal (11:32); he is in life and death(4:5), and as you have already rightly mentioned, if he is himself in life and death then how can he provide salvation to Arjun and others!
 
Kaal himself says in 7:18 that my kind of salvation is anuttam because if there is a superior God to him (15:17) then that God's salvation must also be superior to that of the salvation provided by Kaal.
In 7:29 Kaal talks about Tat Brahm (That Supreme God). Arjun then questions Kaal in 8:1 and asks about Tat Brahm. In 8:3 Kaal answers Arjun and tells hims that "Tat Brahm" which "That God" is "Param Akshar Brahm" (Supreme God). Here Kaal talks about "that" God not himself!
 
In 15:4 Kaal very clearly explains about Tat Brahm and endorses that he himself is also in the refuge of that Supreme God and this Supreme God  is the one who should be worshipped.
 
Then In 18:62 Kaal is instructing Arjun to go in to the refuge of some other God to attain eternal peace and eternal lok (Shashvat sthaan/satlok). In 18:64 he claims that this God that he is talking about is also his God (Isht dev/Pujya Dev). Then in 18:65 he again talks about himself and says to Arjun that if he worships Kaal then he will remain in Kaal's refuge. Finally in 18:66 Kaal asks Arjun not to despair and to go in to the refuge of that One Supreme God.
 
Kaal has given all level of information in Gita from his way of worship (8:13) to the way of worship of that Supreme God (Param Akshar Brahm) (17:23). Now it is down to a sensible "gyaani" soul to decide Which God to worship - the Superior most Supreme God or Kaal who will eat everyone (11:29, 11:30)
Refer: http://www.bhagwadgita.jagatgururampalji.org